micro/sync/cron.go

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package sync
import (
"fmt"
"math"
"time"
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"github.com/micro/go-micro/sync/leader/etcd"
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"github.com/micro/go-micro/sync/task"
"github.com/micro/go-micro/sync/task/local"
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"github.com/micro/go-micro/util/log"
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)
type syncCron struct {
opts Options
}
func backoff(attempts int) time.Duration {
if attempts == 0 {
return time.Duration(0)
}
return time.Duration(math.Pow(10, float64(attempts))) * time.Millisecond
}
func (c *syncCron) Schedule(s task.Schedule, t task.Command) error {
id := fmt.Sprintf("%s-%s", s.String(), t.String())
go func() {
// run the scheduler
tc := s.Run()
var i int
for {
// leader election
e, err := c.opts.Leader.Elect(id)
if err != nil {
log.Logf("[cron] leader election error: %v", err)
time.Sleep(backoff(i))
i++
continue
}
i = 0
r := e.Revoked()
// execute the task
Tick:
for {
select {
// schedule tick
case _, ok := <-tc:
// ticked once
if !ok {
break Tick
}
log.Logf("[cron] executing command %s", t.Name)
if err := c.opts.Task.Run(t); err != nil {
log.Logf("[cron] error executing command %s: %v", t.Name, err)
}
// leader revoked
case <-r:
break Tick
}
}
// resign
e.Resign()
}
}()
return nil
}
func NewCron(opts ...Option) Cron {
var options Options
for _, o := range opts {
o(&options)
}
if options.Leader == nil {
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options.Leader = etcd.NewLeader()
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}
if options.Task == nil {
options.Task = local.NewTask()
}
return &syncCron{
opts: options,
}
}